+0  
 
0
111
6
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Find the sum 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + ... + 301 + 302.  (The pattern of signs is + + - - + + - - ...)

 Dec 3, 2019
 #1
avatar+1068 
-1

1+2-3-4 = -4

5+6-7-8 = -4

And so on. 

Find the number of -4's

 Dec 3, 2019
edited by CoolStuffYT  Dec 3, 2019
 #2
avatar
0

Evaluate the terms whenever one + + - - occurs.

 

For example.

 

1 + 2 - 3 - 4 = -4

 

5 + 6 - 7 - 8 = -4

 

Then find how many +  + - - s are there

 Dec 3, 2019
 #3
avatar
0

i am clacuser not lgged in

Guest Dec 3, 2019
 #4
avatar+1068 
-1

Hey calcuser

CoolStuffYT  Dec 3, 2019
 #5
avatar+2847 
0

yup the next 3 week will be a tornado

CalculatorUser  Dec 3, 2019
 #6
avatar+24376 
+2

Find the sum 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + ... + 301 + 302.  
(The pattern of signs is + + - - + + - - ...)

 

\(\begin{array}{|rll|} \hline && 1 \\ && \underbrace{+2 - 3}_{-1} \underbrace{ - 4 + 5}_{+1}\\ && \underbrace{ + 6 - 7}_{-1} \underbrace{ - 8 + 9}_{+1} \\ && + \ldots \\ && \underbrace{+298 - 299}_{-1} \underbrace{-300 + 301}_{+1} \\ && + 302 \\ &=& 1+0+302 \\ &=& \mathbf{303} \\ \hline \end{array} \)

 

laugh

 Dec 3, 2019

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